The synthesis, X-ray crystal structures, and some spectroscopic and chemical properties of the nitrosylruthenium(II) porphyrin complexes Ru(TPP)(NO)(ONO), Ru(TPP)(NO)(OH), Ru(OEP)(NO)(ONO), and Ru(OEP)(NO)(OH) (TPP = tetraphenylporphyrinato dianion; OEP = octaethylporphyrinato dianion) derived from the analogous Ru(II) carbonyl complexes are reported. Also described are experiments which quantitatively demonstrate that N2O is formed as a product of the synthesis scheme and that NO serves as the principal oxidant in the transformation of N(II) to N(III). The two TPP complexes are isostructural and consist of columns of molecules stacked along the c axis. The two OEP complexes are also isostructural and can be considered as layers of OEP complexes stacked along the b axis with solvent molecules situated at the cavities between layers. The nitrite ions are coordinated in a unidentate fashion through the oxygen atom. Crystal data for Ru(TPP)(NO)(ONO) (1): M = 789.79, space group I4/m (no. 87), a = 13.6529(6) Angstrom, c = 9.7904(5) Angstrom, V = 1825.0(2) Angstrom(3), Z = 2, rho = 1.437 g cm(-3), purple bipyramid, 2 theta(max) = 50.0 degrees, R(F) = 4.87% for 86 parameters and 838 reflections with I > 2 sigma(I). Crystal data for Ru(TPP)(NO)(OH) (2): M = 760.79, space group I4/m (No. 87), a = 13.5423(4) Angstrom, c = 9.7150(4) Angstrom, V = 1781.7(1) Angstrom(3), Z = 2, rho = 1.418 g cm(-3), dark red plate, 2 theta(max) = 50.0 degrees, R(F) = 3.92% for 83 parameters and 811 reflections with I > 2 sigma(I). Crystals data for Ru(OEP)(NO)(OH). C2H5OH (4): M = 726.91, space group P2(1) (No. 4), a = 10.8474(7) Angstrom, b = 21.002(1) Angstrom, c = 8.3646(5) Angstrom, beta = 103.571(1)degrees, V = 1852.4(2) Angstrom(3), Z = 2, rho = 1.303 g cm(-3), brown plate, 2 theta(max) = 45.0 degrees, R(F) = 6.74% for 421 parameters and 3527 reflections with I > 2 sigma(I).